Yeast appears active after 14d but, could it be done? (WLP077)

Question

NE style pale ale, OG 11.5P (1046), hit FG around day 7, 3.1P (1012) for 75% attenuation, which is the low end of the strain.

First time fermenting under pressure, kept at around 0.6bar as of day 3, then to 1.6bar on day 5 when 2P away from FG to 100% carb naturally.

I’m at day 14 now and there are still a stream of tiny fine bubbles coming out of the spunding valve. The sight glass still shows yeast activity with CO2 bubbles carrying yeast up and things swirling around.

Been waiting around 5 or so days for this activity to subside but it just keeps going.

I thought it could be 1) it’s still fermenting, 2) it’s infected and I’m seeing bacterial activity and 3) due to being fully carbed co2 is coming out of suspension and is giving the appearance of active fermentation and carrying yeast up and down the vessel.

Anyone ever experienced this and concluded what could be happening?

I just set the temp to 4c serving temp as it almost has to be either theories 2 or 3 above.

Answer 1

After 14 days, it's most likely done and #3 is your best bet. The best way to tell for sure is take two gravity readings a few days apart. If it hasn't changed, fermentation is finished.

Answer 2

The only way to be sure is to take a gravity reading. That being said - and considering you are fermenting under pressure - it's most likely the CO2 that's causing the activity. If you don't see massive pressure differences (e.g. it isn't going up anymore). It's probably done.